Clinical predictors of asthmatics in identifying subgroup requiring long-term tiotropium add-on therapy: a real-world study

Background: According to several phase III studies, tiotropium [a long-acting muscarinic antagonist (LAMA)] is a well-tolerated add-on therapy to inhaled corticosteroids (ICS) for asthmatics with or without the addition of long-acting beta2-agonists (LABAs). However, real-world studies based on clinical phenotypes to predict the long-term need of tiotropium as an add-on therapy for asthmatics are limited. Methods: This is a retrospective study conducted at a single medical center in Taiwan from July 2016 to July 2018. An asthma control test (ACT) is applied to uncontrolled asthmatics to evaluate the effectiveness of tiotropium as an add-on therapy. Asthmatic subgroups with different clinical phenotypes and needing long-term tiotropium as a maintenance treatment are identified. The effectiveness of tiotropium add-on therapy is defined as an improvement of ACT score ≥3 points 3 months after the treatment (vs. baseline), while the long-term requirement of tiotropium is defined as tiotropium dependency >1 year. Results: The study analyzed a total of 160 uncontrolled asthmatics regardless of low- or medium-to-high-dose ICS plus LABA. One hundred and twelve patients responded well (ACT score increased ≥3 points) to tiotropium. These patients were further divided into two subgroups: one with tiotropium add-on therapy for ≥1 year due to patients’ difficulties in stepping down from tiotropium; the other with tiotropium add-on therapy for 30 kg/m2 were predictors for asthmatics requiring long-term tiotropium add-on therapy. Conclusions: Tiotropium add-on therapy is effective for uncontrolled asthmatics. Moreover, patients with ACO, initial FEV1% predicted 30 kg/m2 require long-term tiotropium add-on therapy for asthma control.